1. Field of the Invention
The present general inventive concept relates to an image forming apparatus to cope with an error of a controller to control a fusing temperature.
2. Description of the Related Art
An electrophotographic image forming apparatus, such as a printer, multifunction printer or the like, includes a fusing device for fusing a toner image transferred onto print paper.
The fusing device is adapted to actuate a heater through a controller to melt toner powder transferred onto the print paper.
The controller is adapted to control a fusing temperature based on a predetermined reference fusing temperature to cope with an excessive increase in the fusing temperature resulting from a malfunction in the fusing device or an electric circuit supplying power to the heater.
Together with this operation of controlling the fusing temperature, the controller acts to perform an operation of compulsorily cutting off power to the heater by a bimetal when the fusing temperature increases excessively.
On the other hand, the heater may be erroneously actuated due to an abnormal output of the controller. Where the heater is erroneously actuated in response to a control command from the controller, the fusing temperature rises. At the time that the fusing temperature rises excessively, the actuation of the heater is stopped by the bimetal and the fusing temperature thus falls. However, even though the fusing temperature falls just a little, the cut-off operation by the bimetal is released, so that the heater is again actuated by the control command from the controller. As a result, in spite of the fact that a fusing process is not actually required, a high fusing temperature may be maintained due to a wrong control command resulting from an error in the controller, so that the fusing device may be so overheated as to melt the structure thereof.